Forwarded from Jerry Leverenz
-Toby Bradshaw
toby at u.washington.edu
---------- Forwarded message ----------
Date: Mon, 09 Oct 1995 16:55:51 +0100
From: Jerry Walter Leverenz <Jerry.W.Leverenz at botge.kvl.dk>
Assuming you have not fogotten to take into account differences in root
production. Note that on good sites it is very unlikely that differences in
root production will not explain a doubling of production. Although
differences in root respiration may also have to be taken into account. OK
so provided there are no differences in root production (or a large
difference in irradiances at the sites) the answer probably lies in increased
photosynthetic efficiency at low light. This difference in efficiency allows
both the higher LAI and a higher production, see Leverenz & Hinckley
1990, Tree Physiology 6:135, Leverenz 1992, Scand. J. Forest Res.
7:345-353, and Leverenz 1995, Funct. Ecol 9:413-421. Such efficiencies
are almost certainly related to small scale architecture, such as leaf
arrangement of shoots and whether the shade leaves are held flat or if the
individual leavea are curled or bent as a result of a lack of stiffness. Based
on absorbed light photosynthetic efficiency at low light is constant for C3
plants at a given temperature. Of course, perhaps the differences may be
due differences in temperature at the two sites? Have you checked this
possibility?
Jerry Leverenz